Olfactory cleft and sinus opacification differentially impact olfaction in chronic rhinosinusitis

Objectives: Prior studies have indicated that olfactory cleft (OC) opacification correlates with olfaction in patients with chronic rhinosinusitis (CRS). However, the results have been unclear in patients without polyps. The purpose of this study was to further explore the relationship between OC opacification, sinus opacification, and olfactory function in patients with CRS. Methods: One hundred and forty-eight patients with CRS were prospectively enrolled across five institutions. Olfactory function was evaluated using the Sniffin’ Sticks tests (Burghardt, Wedel, Germany) and the 17-item Questionnaire of Olfactory Disorders (QOD-NS). Computed tomography (CT) scans for each patient were acquired and Lund-Mackay scores recorded. Opacification of the OC was determined using OsiriX MD (Pixmeo, Bernex, Switzerland) and correlated with olfaction scores. Results: A total of 148 CRS patients, 73 CRS without nasal polyps (CRSsNP) and 75 CRS with nasal polyps (CRSwNP), as well as 30 control subjects were enrolled. Overall OC opacification averaged 63.7% in CRS patients and 47.1% in control subjects (P < 0.001). In the overall cohort, OC opacification significantly correlated with threshold, discrimination, and identification (TDI) (r = −0.520; P < 0.001) and QOD-NS scores (r = 0.374; P < 0.001). CRSwNP patients demonstrated a significant correlation between OC opacification and TDI scores (r = −0.464; P < 0.001) but not the CRSsNP group (r = −0.143; P = 0.229). Lund-Mackay score correlated with TDI in both the CRSsNP (r = −0.300; P = 0.010) and CRSwNP (r = −0.271; P = 0.019) groups. Conclusion: CT opacification is associated with olfactory dysfunction differentially based on nasal polyp status. Smell loss in CRSwNP correlated with both OC opacification and Lund-Mackay score, whereas CRSsNP correlated only with Lund-Mackay score, indicating different relationships between olfactory function and local inflammatory processes in these disorders. Level of Evidence: 2 Laryngoscope, 130:2311–2318, 2020.